The present invention relates to methods for converting butadiene to aromatic compounds.
Ethylbenzene is an important commercial solvent and a precursor to styrene. Styrene is a major commercial chemical which finds its principal use in the manufacture of polymers such as polystyrene. Typically, styrene is formed by the dehydrogenation of ethylbenzene. Both ethylbenzene and styrene may be produced by catalytic dehydrocyclization of 4-vinylcyclohexene ("VCH") by use of various known catalysts. Two-step processes for producing styrene and ethylbenzene are also known wherein butadiene is dimerized to form VCH and the VCH is then catalytically aromatized.
However, the prior art lacks methods of producing styrene and ethylbenzene directly from butadiene. Methods for the aromatization of VCH, moreover, have been plagued with poor yields and large amounts of by-products such as xylene with are extremely difficult to separate from the desired products.
For example, Suzuka et al. sealed magnesium oxide and butadiene in a quartz reactor at 200.degree. C. for 17 hours to produce ethylbenzene in a yield of about 17 percent. Applied Catalysis, Vol. 47, L7-L8 (1989). However, the major product of the reaction was o-xylene in a yield of about 54 percent.
What is needed are new, more selective and effective processes for the production of aromatics such as ethylbenzene and styrene which alleviate problems in the prior art. What is also needed is a process to produce aromatics directly from butadiene thereby offering a new method of producing the aromatics in one step.